A study of the drying potential of various wood frame wall systems used in Atlantic Canada.

The concern that a large number of housing units across Canada, and in particular, through Atlantic Canada are exposed to potential damage from wood rot due to moisture trapped within exterior walls caused a joint task force of Canada Mortgage and Housing Corporation and Canadian Home Builders Association representatives to address the "drying of walls" issue. Included in their mandate was a field research project in Atlantic Canada. The project, undertaken by Oboe Engineering Ltd. and AD1 Limited. for the Project Implementation Division of CMHC, involved the erection of test huts in Halifax, Nova Scotia; Fredericton, New Brunswick; and St. John's, Newfoundland and the monitoring of the performance of eight different types of wall construction for a one year period. To assess the drying rates, the wall panels used in this experiment were intentionally designed with saturated lumber. As such, high values of equilibrium moisture content recorded and presented in this report, must be amsidered in relation to the design of the experiment, and not a function of the products or materials incorporated in any particular wall assembly. The experimental procedure involved mnitoring temperature., relative humidity, pressure, structural moisture content, wind speed and direction, and presence of condensation in each wall panel, in each city, each hour, for one year. This report presents an overview of the results, global trends in the drying of walls, and the sensitivity of wall permeance, geographic location, compass heading and presence or absence of furring strips to wall drying.